A 50 year old otherwise healthy woman presents to your clinic with intermittent rectal pain that no one can diagnose. She has severe attacks of anorectal pain lasting from a few seconds to minutes. The attacks are infrequent, less than five episodes a year, and she is asymptomatic between episodes. They happen day or night, without any specific triggers, unrelated to bowel movements. She has seen multiple gastroenterologists, gynecologists, surgeons, and other physicians who have found nothing wrong. Physical exam, lab tests, CT scan, MRI, anoscopy, and colonoscopy have yielded nothing abnormal. Anorectal manometry is normal.
Challenge: What is this called?